Improvement in steam-pumps



` Lwlsfemsconl. Improvement in Steam Pumps.

UNITED STATES i PATRQEEICE. i

LEWIS GEIscoM, or PORT CARBON, PENNSYLVANIA, AssIeNoE ToEIM sELE, cEALkLEY eEIsooM, AND `Joan r., eEIsooM, oE sAME PLACE.

|MPRQVEMENT IN .STEAM-PUMPS.

Specification forming part of Letters Patent No. 124,679, dated March 19, 1872.

' ing to be a full, clear, and Vexact description thereof, which will enable others skilled in the art to which it appertains to' make and use my invention, reference being had to the accompanying drawing which forms a part of this specification, and in Which- Figure 1 represents my invention in side ele- -vation. Fig. 2 is a plan or top view thereof;

and Figs. 3, 4, and 5 represent diii'erent positions of the valve.

The same parts are denoted by the same letters in all the figures. This invention relates to that class of steampumps which are known as crank steampumps, and in which motion is communicated to the stem of the valve which admits steam to the cylinder, through the intervention of a revolving crank-shaft, on which is keyed the eccentric by whose rod the valve-stem is Worked, the crank being rotated by the reciprocating movement of the piston-rod or pump-rod, to which it is connected by a slotted cross-head, connecting-rod, or equivalent device. The operation of such pumps has hitherto been attended with a serious difiiculty, the nature of which will be understood by comparing them with ordinary steamengines. In a steam-engine of the usual construction, as no rotating effect is produced on the shaft when the crank is on the dead-center, and very little until the crank-pin has passed some distance beyond the center, the steam. must not be admitted too quickly at the beginning of the stroke; for in that case its force, instead of rotating the crank, would be thrown on the bed-plate and its connections. In a pump, on the other hand, where the power is exerted directly-through the piston-rod and plunger to overcome the inertia of the whole mass of water at the beginning of the stroke, the full pressure of steam should be admitted as early as practicable. Hitherto, however, this difference has not been recognized in the construction of crank-pumps. Their valvestems being actuated by means of 'the ordinary eccentric, the full pressure oi steam is not admitted as early as the conditions ot' their operation require, and the momentum of the ily-wheel and other revolving parts is consequently exerted against the water, resulting in a severe strain on the `crank-pin and its bearings, as wellas on the crank-shaft, cross-heads, connecting-rods,bedplate, &c., sometimes breaking said shaft, dragging the crank-pins out of place, increasing the wear on their bearings, and invariably causing thumping and lost motion. To obviate this difficulty (which increases rapidly with increased size of pump and pressure of Water in the discharge-pipes) is the object of f my invention; and it accordingly consists in the means hereinafter described whereby the full pressure of steam is admitted to the steamcylinder sooner than can be done by the ordinary eccentric.

l A inthe drawing represents the steam-cylinder; B, the piston-rod; C, the cross-head; D, the pump-rod; and E, the water-cylinder. F

is the guide on which the cross-head C slides to and fro. The cross-head is grooved or slotted to receive the pin Gr of the crank-arm H, attached to the shaft I. To this shaft I is secured the cam J, which I prefer to make of the form commonly known as a D-cam, alalthough various irregular forms may be employed. K is the frame within which the cam J revolves, and to which the valve-stem L is secured.

Fig. 3 represents the position of the cam and valve, when the crank is on the center,

as shown in Fig. l. This position is the same whether the valve be worked by a cam or by the ordinary eccentric. In Figs. 4 and 5 the crank has traveled about thirty-seven degrees from the center. ln Fig. 4 is shown the operation of the c'am which has fully opened the steam-port, while in Fig. 5 the valve controlled by the ordinary eccentric has opened it only about one-half. By thus using a cam ofthe form shown, orof any other well-known form which will operate thc valve-stem at the vbeginning of the stroke more rapidly than lis done by the eccentric, the force ot' the steam is exerted on the Water at the earliest instant, and the `'evolving parts are relieved from the strain. above described.

I have shown this invention as applied to a slidevalve; but it may evidently be applied to puppet or other va1ves,the cameframe being connected therewith in the same manner as the eccentric strap. The details of construction may also be varied Without departing substantially from the arrangement which I have described; for example, the crank may be rotated by the usual connecting-rod attached to the piston-rod, or by any other Wellknown substitute for the grooved cross-head, and other variations of detail will readily suggest themselves.

What I claim as my invention, and desire to secure by Letters Patent of the United States, ist v The arrangements, substantially as herein described, of the steam-cylinder A, Water-cylinder E, piston-rod B, pump-rod D, grooved or slotted cross-head O, crank-pin G, crank H, crank-shaft I, cam J, and devices connected with said cam to actuate the valve.

LEWIS GRISCOM.

Witnesses:

LEONARD MERTs, JOHN L. SHIssLER. 

